At 73, Ray Umashankar likes to stay active. He walks four miles around his Tucson, Arizona, neighborhood every day and works out at the gym with his wife three times a week.

That’s not the only way he’s unstoppable. Along with his daughter, Nita, Umashankar is responsible for having educated more than 1,500 women and children rescued from human trafficking in India through a project called Achieving Sustainable Social Equality through Technology (ASSET) India Foundation—a project he took on less than a decade ago.

Exact numbers are difficult to find, but the U.S. State Department estimates that between 20 million to 65 million Indian men, women, and children are forced into hard labor and sex trafficking, from rice mills and embroidery sweatshops to domestic servitude and sex slavery. Experts estimate that millions of Indian women and children are victims of sex slavery.

It’s a huge problem, and solving it entirely will take time and effort. But it’s an effort Umashankar was willing to make after Nita brought him the idea of training girls rescued from sex trafficking and children of sex workers in higher-paying technology jobs when he was 64. Though he could have retired instead, he readily accepted the challenge.

“Nita gave me a purpose for my life,” he said. “Now I’m in daily contact with her."

That alone is enough to inspire admiration from one major donor in India, a multimillionaire who sold his company to a major IT company and tells Umashankar that he hopes to build something with his daughter someday too.

“This guy is living in a mansion, driving a Ferrari, and he wants something that I have,” Umashankar said.

Umashankar’s program teaches vulnerable young women ages 14 to 28 basic English and marketable tech skills, such as data entry and office-suite software applications, that help them open doors where taboo about their past may have locked them out of opportunities.

In 2008, two years after the father-daughter team started the project, Nita was busy with her master’s degree and Umashankar was sending relentless emails to CEOs and millionaires to get his story heard and get funded.

“There was a foundation president in D.C. who kept putting me off,” he remembers. “Finally, I had to go to a wedding in Virginia. I called her up and said, ‘How about we meet?’ ”

The woman put Umashankar off, saying she needed to take her daughter to piano lessons and run errands. “I said, ‘Great! I have a rental car. I can pick you up, and we’ll run errands,’ ” Umashankar recalls.

When he left her home, he had a check for $10,000 in his hand. This never-say-no attitude is exactly why he was awarded a prestigious Purpose Prize from Encore.org in 2008, an award given to inspiring over-60 individuals who take on tough social problems in creative ways.

“Now I send a link to the Purpose Prize in my emails to CEOs,” he said. “It has a tremendous impact in establishing credibility that our work has been recognized by Encore.”

Seven years later, Umashankar has been able to leverage the Purpose Prize to raise hundreds of thousands of dollars and equipment donations and solidify partnerships with luminaries such as Nobel Peace Prize winner Kailash Satyarthi. This year, Umashankar and Satyarthi are embarking on a joint project to bring a traveling education program to 400 Indian villages, so young women and children can learn their rights and how to protect themselves from human traffickers.

His projects go a step further than education. His next venture has ASSET partnering with the inventor of a low-cost sanitary napkin that can be distributed to schools all over the country.

“I looked into why they stopped going to school,” he said. “I asked the girls, and the girls were very bashful, and then I asked the social workers, the teachers. In rural India, when the girls start menstruating, they use dirty rags, and they get sick, and out of embarrassment, they stop going to school. Providing proper sanitary napkins, making them available, that’s going to keep them in school.”

He makes pacts with ASSET students’ mothers now, holding the whole family responsible for the progress of the girls. He tells them that any obstacle they have, whether it be travel costs or help at home, ASSET will help these girls finish school.

“I came to the U.S. when I was 26,” he said. “When I’m in India now, they want to question my motives and why am I doing what I’m doing. I tell them life in the U.S. is like eating dessert three times a day. This is what I tell the students: You’ll get tired and sick if you eat dessert three times a day.”

He thinks showing by example how he supports his daughter through her own struggles—juggling a new baby, a professorship, and ASSET—also gives the families confidence that if they follow through, Umashankar will help.

In 2013, he even quit his assistant dean position at the University of Arizona to focus on setting up ASSET financially so Nita can continue her work with India’s women and children far into the future. He quit watching TV, quit watching sports—even his favorite team, the Redskins—and devoted his life to ASSET. It’s the ultimate gift a father can leave his daughter, but Umashankar insists it was Nita who gave him a gift of inspiration.

“Nita was a classically trained dancer, and at the end of her training, tradition is that she gives her first public performance, and people give her gifts. But she said, ‘I don’t want to give any gifts. If you are interested, you can give a donation for this home for abused women and children.’ She got $7,800 to donate. This was all her. It’s what makes me feel greatest as a parent, as a person.”

• A Wolfe has covered arts, entertainment, and politics for Good, Vice, Flaunt, and other publications.